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IPlayer TV
General technical overview Programme IDs All programme episodes on BBC TV are assigned a programme ID (PID) made up of lower-case letter and numbers of around 8 characters. More information on the format of the PID's can be found at the BBC Programme Guide. For Instance for Torchwood, you can see which programmes are available on iPlayer. In addition to this, it is possible for episodes in iPlayer to have several published "versions". Every episode of a programme should have at least one version - the "original". Other versions that exist are: Retrieving programme meta-data Detailed metadata can be retrieved from XML resources available for each episode with URLs of the form http://www.bbc.co.uk/iplayer/metafiles/episode/.xml This contains information on the episode versions available and descriptive information on episodes including still image URLs. This information appears to also specify some of the "More Like This" programs. Different programme metadata is available at: http://www.bbc.co.uk/iplayer/playlist/ The 'version pid' is within the '' tag under the 'item' tag which has the 'kind=programme' Retrieving programme media stream information This URL contains an entry for each of the different streams associated with the spefici version of a particular programme: http://www.bbc.co.uk/mediaselector/4/mtis/stream/ It typically contain entries for: * captions (e.g. subtitles) * video (e.g. h.264, VP6 and Spark) * audio (e.g. real and mp3) Subtitles Subtitles are available on some iPlayer programmes. The subtitles are in W3C Timed-Text format. The S button on the Flash based iPlayer makes use of this file. The URL for a specific subtitle feed is determined by obtaining the 'version pid' for the programme. Retrieving programme media stream information as described above. It will have a stanza with something like: The subtitle feed can be downloaded from the URL pointed to in the href field, e.g.: http://www.bbc.co.uk/iplayer/subtitles/b0008dc8rstreaming89808204.xml Scripts and programs See Programs Windows P2P Version See Windows P2P Flash / RTMP Version See Flash iPlayer iPhone Version See IPhone H.264 version Nokia N96 / RTSP Version See Nokia H.264 version Note about technical image quality Please note: the technical image quality varies widely across the different versions of iPlayer output, particularly between the DRM-enabled version for Windows, and the iPhone version. Taking one program as an example, "House of Saddam" episode 1, broadcast on Wed 30th July 2008, the compression details are as follows: Windows DRM version Windows Media 9 video compression, 672x544 pixels, overall bit-rate (complete file including video and audio): approx 608 Kbit/s. Of this, the video is estimated as approx 475 Kbit/s, and the Windows Media Audio 9.1 stereo, 44KHz, is approx 128 Kbit/s. The video could be described as "VHS quality". iPhone version H.264 compression, 483x272 pixels, overall bit-rate (complete file including video and audio): approx 512 Kbit/s. Of this, the video is approx 395 Kbit/s, and the AAC audio is approx 113 Kbit/s. The video could be described as "definitely below VHS quality". Therefore whilst the iPhone-service download tools do allow BBC license payers to access non-DRM version of the BBC content, it should be noted that the video quality achieved will be noticeably less than what is available through the DRM-protected service. Nokia N96 / RTSP version Codec: H.264, Video Resolution: 320x176 pixels, Overall bit-rate: approx 256 Kbit/s. mp4a audio is used, Quality: well below VHS quality Flash/RTMP version (standard quality) Codec: On2 VP6, Video Resolution: 512x288 pixels, Overall bitrate: approx 500 Kbit/s, Quality: "definitely below VHS quality" Flash/RTMP version (high quality) Codec: H.264, Video resolution 640x360 pixels, Overall bitrate: approx 800 Kbit/s, Quality: "near-VHS quality".